Thermal receptacle with phase change material containing insert

ABSTRACT

A thermal receptacle having a side wall which has an inner surface and a spaced outer surface. An interstitial chamber may be defined by the space between the inner and outer surfaces. A phase change material containing insert is provided into the receptacle. The insert contains a phase change material or a plurality of different phase change materials. Phase change material may also be located within the interstitial chamber. The phase change material regeneratively absorbs thermal energy from a hot liquid in the receptacle thereby rapidly lowering the temperature of the liquid and then the material releases the thermal energy back to the liquid to maintain the temperature of the liquid.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser. No. 61/583,888, filed Jan. 6, 2012, and incorporated herein by reference.

TECHNICAL FIELD

The subject invention relates generally to liquid receptacles or containers and more specifically to a receptacle having a phase change material insert and which rapidly cools a hot liquid (or heats a cold liquid) to a desired range and then maintains the fluid in the desired range for an extended period.

BACKGROUND OF THE INVENTION

There have been many attempts in the past to maintain liquids and solids within certain temperature ranges. Hot beverages are usually prepared and served at temperatures well above the desired temperature range of consumption. Typically, the consumer must wait some time before the beverage to sufficiently cool before drinking it. Some impatient consumers will attempt to drink the beverage too soon resulting in burns to the mouth. Similarly, if the drink is spilled before it has had sufficient time to cool, burns to the skin may result. Therefore, it is desirable to rapidly cool the beverage from the temperature at which it is served to an acceptable temperature range for consumption. Once the beverage is within the acceptable drinking temperature range, it is desirable to maintain the temperature of the beverage within this range for as long as possible.

Many approaches have been tried for both rapidly cooling a hot beverage and for maintaining the temperature of the beverage within an acceptable drinking temperature range. To rapidly cool a hot beverage, ice or a cool liquid (e.g., water or milk) can be added to the hot beverage. This approach rapidly cools the beverage but dilutes the hot beverage. This is frequently undesirable. This approach is often inconvenient and imprecise; if the person adds too little or too much, the temperature of the hot beverage will be higher or lower than desired and may require further attention. Finally, this approach does not provide any assistance in maintaining the temperature of the hot beverage in the acceptable drinking temperature range. Once the beverage reaches an acceptable temperature, it will continue to lose thermal energy to its surroundings. This results in the beverage becoming cool too quickly. Therefore, the beverage remains within an acceptable drinking temperature range for only a short period.

A hot beverage can also be cooled by pouring it into a cool container. Thermal energy is transferred from the hot beverage to the cool container thereby warming the container and cooling the beverage. This approach suffers from some of the same limitations as adding cool liquid or ice. If the cup is too cool or too warm or has too much or too little thermal mass, the beverage will stabilize at the wrong temperature. Also, while a heavy container will slow the rate of cooling somewhat due to the increase in the total thermal mass of the system, the effect will be small and the beverage will only remain in the ideal drinking range for a short period.

One primary method employed for slowing the cooling rate of a beverage has been to insulate the container. Everything from simple foam cups to expensive and sophisticated vacuum insulated mugs have been used. These approaches slow the cooling rate of the beverage. However, the ability of the insulated mugs currently on the market to maintain beverage temperatures is relatively limited. Stainless, vacuum insulated mugs are excellent at maintaining temperature, but no product currently exists which can passively cool a hot beverage quickly. Also, the beverage in an insulated container will continue to cool despite the insulation. The cooling rate will only be slowed. Insulation does not provide a way to add thermal energy back to the beverage.

SUMMARY OF THE INVENTION

This invention addresses the need to rapidly lower the temperature of a hot liquid to a desired warm range suitable for human contact and then maintain the liquid in the desired warm range for an extended period of time. The invention includes a liquid receptacle having a side wall with a lower end and an open upper end. A bottom wall closes off the lower end of the side wall. The side wall has an inner surface and a spaced outer surface. An interstitial chamber may be defined by the space between the inner and outer surfaces. An insulation layer can be disposed at least partially between the chamber and the outer surface of the receptacle. A phase change material containing insert is provided into the receptacle. The insert may be fixed in place or may be removable to facilitate cleaning of the receptacle. The insert contains a phase change material or a plurality of different phase change materials. Phase change material may also be located within the interstitial chamber. The phase change material regeneratively absorbs thermal energy from a hot liquid in the receptacle thereby rapidly lowering the temperature of the liquid and then the material releases the thermal energy back to the liquid to maintain the temperature of the liquid.

The present invention is suitable for many applications requiring the rapid lowering of the temperature of a hot liquid in a container and then the maintenance of the temperature of the liquid for an extended period of time. Among other things, the invention can be applied to drinking mugs or cups, baby bottles, carafes, etc. The present invention may also be suitable for rapidly raising the temperature of a liquid in a container and then the maintenance of the temperature of the liquid for an extended period of time.

Embodiments of the present invention may find applicability in diverse uses such as dispensing of medicines and fluids in the life science industries. For example, an embodiment of the present invention may include a vessel for dispensing fluids in a lab or science setting where the fluid is dispensed within a specific temperature range(s).

The demand for hot beverages is very high, especially for coffee and tea, the most popular adult hot beverages. Therefore, it is desirable to develop a reusable beverage container that will rapidly cool coffee drinks to an acceptable drinking temperature, will maintain the temperature within an acceptable temperature range for an extended period, requires neither manipulation by the consumer or the input of external energy, and is portable.

The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention.

DESCRIPTION OF THE DRAWINGS

In the accompanying drawings which form part of the specification and wherein like numerals and letters refer to like parts wherever they occur:

FIG. 1 is a perspective view of an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the vessel of FIG. 1.

FIG. 3 is a perspective illustration of the insert of FIG. 1.

FIG. 4 is a top plan view of the insert of FIG. 3 inserted into the vessel of FIG. 2.

FIG. 5 is perspective view of another embodiment of the invention.

FIG. 6 is a perspective view of another embodiment of the insert of FIG. 1.

FIGS. 7 and 8 are perspective views of another embodiment of the present invention.

FIG. 9 is a perspective view of yet another embodiment of the present invention.

FIG. 10 is a perspective view of the insert 21 of the receptacle of FIG. 9.

FIG. 11 is a top view of a hollow tube used to form the insert 21 of FIG. 9.

FIGS. 12 and 13 are comparisons of thermal characteristics of a PCM receptacle of the present invention as compared to a control.

DETAILED DESCRIPTION OF THE INVENTION

One embodiment of the present invention is a coffee cup. Such an embodiment can be used for coffee or any liquid that is desired to be brought into and maintained within a desired temperature range. The cup rapidly cools the coffee or liquid by employing phase change materials (PCMs) to help manage the temperature of the coffee. The phase change materials are placed within an insert adapted to be inserted into the cup. Additional phase change materials can be placed inside the cup walls, such as disclosed in U.S. Pat. No. 6,634,417, incorporated herein by reference.

Cup embodiments of the present invention include phase change material in an insert or inserts designed to be placed within the interior of the liquid cavity of the cup. The insert can be of several different designs but each design increases the amount of surface area that is between the coffee and the PCM (as compared to PCM in the walls of the cup alone) thereby increasing the thermal transfer between the hot coffee and the PCM cooling the coffee quicker than a non-enhanced cup or the cup of the previous invention. The more surface area between the hot drink and the PCM the quicker the hot drink will cool.

In one version of the present invention the insert is designed to have hollow fins that extend outwardly from the vertical centerline of the hot drink cup toward the sides of the cup. The hollow portion of the fins are filled with a phase change material or materials with solid/liquid transition temperatures selected to optimize the desired thermal performance of the cup (different people may have cooler or warmer desired coffee drinking temperature ranges). The fins may or may not be attached to the walls of the cup. The finned insert may be a part of the cup itself or be removable from the cup as a separate unit or units. There may be space below the fins to allow coffee to move between the three cavities that are formed by the fins. This may be used in such a manner as to have the first amount of hot drink to be consumed drawn from the bottom of the hot drink cup where the cooler drink will gravitate. This insert may or may not be attached to a removable lid of the hot drink cup.

Another version of the present invention is to place PCM inside of tubing that is formed in a single, double or multiple spiral fashion. The tubing may be attached to a removable lid of the coffee cup.

Embodiments of the present invention may include two or more different PCM's. For example, a single insert may include two or more separate cavities containing two or more different PCM's.

The solid/liquid transition temperature of the PCM is selected to optimize the thermal management performance characteristics of the coffee or other hot drink. Coffee may be introduced into the cup at a temperature that is higher than the desired consumption temperature range. The PCM will liquefy while absorbing heat from the coffee until the coffee is within the desired consumption temperature range or all the PCM has been liquefied. When the temperature of the coffee is below the solid/liquid transition temperature of the PCM the PCM will release heat back into the coffee maintaining the temperature of the coffee within the desired drinking temperature range for a longer period of time that the non-enhanced coffee cup.

The inserts can be engineered to be buoyant or partially buoyant. That means that PCM containing fins or units can be engineered to always “float” towards the top of the coffee in the cup and not above the top of the coffee. This would allow the PCM to absorb heat from the hottest coffee (which will gravitate to the top of the cup) and allow the PCM to release its stored heat back into the coffee itself and not in the airspace above the coffee.

Another application for the invention would be a beer mug. A liquid PCM can quickly warm the beer to its optimal drinking temperature range and keep the beer within the optimal drinking temperature range for a longer period of time that a non-enhanced beer mug.

Another embodiment of the present invention includes a device for dispensing medicines and fluids in the life science industry. For example, an embodiment of the present invention may include a vessel for dispensing fluids in a lab or science setting where the fluid is dispensed within a specific temperature range(s).

Referring to the Figures, wherein like numerals indicate like or corresponding parts throughout the several views, a liquid receptacle is generally indicated at 10 in FIG. 1. The receptacle 10 includes a vessel 12 and an insert 21. Vessel 12 includes an open upper end 13 and a closed lower end 14 and an inner wall 16 connecting the upper 13 and lower 14 ends. An insulated outer shell 18 is spaced from the inner wall 16 defining an interstitial chamber 20 therebetween. In some embodiments of the invention, a phase change material 19 is disposed within the chamber 20, as depicted in FIG. 2. The performance of the receptacle is greatly enhanced by the insulated outer shell 18. The insulation slows the loss of thermal energy from the phase change material thereby greatly extending the period that the beverage can be maintained within the warm range. The insulation may be provided by a vacuum insulation system.

Insert 21 defines a hollow chamber which contains phase change material. Insert 21 may be metal, plastic or another suitable material with one or more hollow cavities. In other embodiments of the invention, insert 21 is constructed of a PCM impregnated material which contains PCM without a large visible hollow cavity. For example, a sponge-type or paper material may be impregnated with PCM and then provided into a container (soft, hard, flexible, etc.) to define the insert 21.

Preferably, the inner vessel 12 and insert 21 are formed of a material having a high thermal conductivity such as aluminum, copper or alloys thereof. A material with a lower thermal conductivity may also be used but the performance of the invention will be reduced accordingly. The inner vessel 12 or insert 21 may be coated, anodized, or plated in order to improve the appearance, resistance to oxidation, or cleanability of the vessel 12 or insert 21. Alternatively, the vessel 12 or insert may be formed from two or more different materials.

FIG. 3 depicts insert 21 as having multiple fins 23. FIG. 4 depicts the insert 21 of FIG. 3 inserted into vessel 12.

FIG. 5 depicts another embodiment of insert 21 inserted into vessel 12. FIG. 6 depicts a generally S-shaped insert 21.

FIGS. 7 and 8 depict another embodiment of the invention wherein the insert 21 is a coiled, close-ended tube containing the PCM. Insert 21 is sized to be received into vessel 12 as shown in FIG. 8.

FIGS. 9-11 depict yet another embodiment of the present invention wherein the insert 21 is defined by a convoluted metal tube 30. Tube 30 is secured to cover 32. A phase change material is contained within the hollow tube 30. The tube ends are sealed to contain the PCM within the tube 30. FIG. 11 shows the tube 30 prior to being bent into the shape of FIGS. 9 and 10. Tube 30 has a length of approximately 10 inches and a wall thickness of approximately 0.020 inches. Tube 30 has a diameter of approximately 0.5 inches. Other embodiments of tube 30 could have different dimensions. In one example, the tube 30 volume is approximately 2 ounces and the vessel contains approximately 16 ounces. Tube 30 may be anodized or coated.

Convoluted metal tube 30 has a significantly increased surface area as compared to a standard tube. It is desirable to maximize the surface area of the insert 21 as the thermal energy exchange rate between the hot liquid and the phase change material is dependent on the surface area of the PCM container. The convoluted metal tube 30 provides an energy efficient, rigid metal structure for containing the PCM. In other examples (not shown), the inner walls of the vessel 12 may also include convolutions if a second PCM is contained within the interior of the vessel 12.

In the embodiment of FIGS. 9-11, tube 30 is secured to cover 32. Cover 32 thus acts to align and hold the insert 21 within the liquid. A sealing structure 34 is provided upon cover 32 to prevent the liquid from escaping the vessel 12 when the cover 32 is secured. Sealing structure 34 may be a flexible sealing ring.

To use the receptacle 10, a consumer removes the lid and pours a hot beverage or liquid into the inner vessel 12 of the receptacle 10, which is initially at room temperature. The thermally conductive material of the insert 21 conducts thermal energy of the hot beverage or liquid into the phase change material. As the phase change material absorbs the thermal energy, the temperature of the phase change material rises from room temperature to its phase change temperature. Preferably, the phase change will be from solid to liquid. Many other phase change materials are also available with acceptable phase change temperatures. One class of phase change materials includes a set of naturally occurring fatty acids with melting points in the range of 110° F. to 160° F. These materials are advantageous due to their non-toxic and relatively innocuous characteristics. As will be clear to one of skill in the art, many materials are available which can be used as phase change materials. However, to be useful for thermal management, a material must change phases at a temperature close to the temperature range desired to be maintained. Also, it is desirable that the material be non-toxic and be readily available at a reasonable price.

Once the phase change material reaches its melting point, the temperature of the phase change material will no longer rise as the thermal energy is absorbed causing the material to melt (change phases). As the phase change material absorbs thermal energy from the hot beverage, the temperature of the hot beverage will fall. The temperature of the hot beverage will continue to fall until the beverage and the phase change material are in thermal equilibrium; e.g., they are at the same temperature. The quantity of the phase change material is chosen so that during its phase change it can absorb enough thermal energy to cool the hot beverage from the boiling point of water down to within a warm range acceptable for human consumption. Once the hot beverage is cooled to within the warm range, the beverage and the phase change material are at equilibrium and the beverage is drinkable. As the beverage loses thermal energy to the surrounding atmosphere, its temperature will begin to fall below the phase change temperature of the phase change material. At this point, the phase change material will begin to transfer thermal energy back through the insert 21 into the beverage. This thermal energy will maintain the temperature of the hot beverage near the phase change temperature of the phase change material as the phase change material resolidifies. Once the phase change material converts back to the solid phase, its temperature will begin to fall and the beverage temperature will no longer be maintained. Because the phase change material remains at the phase change temperature during the phase change, the beverage will be maintained near the phase change temperature for an extended period.

In another method of using the receptacle 10, the insert 21 is actively pre-treated prior to insertion into the liquid. For example, the insert 21 may be heated just prior to use of receptacle 10. An active heating element (not shown) may be used to pre-heat the insert 21 prior to insertion into a hot liquid. For example, insert 21 may include a resistive element which is used to heat the insert 21. In another example insert 21 is passively heated by an external heat source. Additional thermal benefits are obtained by thermally pre-treating the insert 21 or vessel 12 or both.

Referring now to FIG. 12, the thermal characteristics of the receptacle 10 adapted for hot beverages for adults are shown. The graph shows the temperature of a hot beverage poured into a typical prior art plastic coffee mug (the “Control”). The temperature of the beverage falls slowly but steadily to the upper limit of the warm range (labeled as Drinking Temperature Range) acceptable for human consumption, which in this example is approximately 65° C. The temperature of the beverage continues to fall until it falls below the lower limit of the warm range which in this example is approximately 55° C. Consequently, the beverage is only within the warm range or acceptable drinking temperature range for a short period of time.

The data labeled as “PCM Mug” illustrate the thermal characteristics of a receptacle constructed according to the present invention. The datapoints indicate the temperature of a hot beverage poured into the receptacle versus time. The beverage cools very rapidly as the thermal energy of the beverage is absorbed by the phase change material. The beverage rapidly falls to the upper limit of the warm range and then the cooling rate slows. The beverage remains within the warm range for an extended period as compared to the control.

Referring now to FIG. 13, a comparison was made between the thermal characteristics of receptacle 10 having a PCM insert 21 versus a receptacle without the PCM insert 21 (“control”). The PCM data depict temperature characteristics of a receptacle having PCM insert 21. The graph depicts the temperature of a 15 ml amount of liquid poured from the receptacle 10 and control receptacle. As shown, the receptacle 10 with the PCM insert 21 provides the decanted liquid within the desired temperature range (65° C. to 50° C.) for a significantly longer period of time in comparison to the control. The PCM mug maintains the liquid within the desired temperature range for more than twice as long as the control mug. The PCM mug maintains the temperature within the desired range from period, t1 to t3. In comparison, the control mug maintains the temperature within the desired range from period, t2 to t3.

Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps. 

What is claimed is:
 1. A liquid receptacle comprising: a vessel having an open upper end and closed lower end and a wall connecting said upper end and said lower end; and a phase change material disposed within an insert, said insert adapted to be placed within said vessel for regeneratively absorbing thermal energy from the liquid and then releasing the thermal energy to the liquid to maintain the temperature of the liquid within a desired temperature range.
 2. The liquid receptacle of claim 1 wherein the insert is secured to a sealing cover.
 3. The liquid receptacle of claim 2 wherein the insert is a closed tube.
 4. The liquid receptacle of claim 3 wherein the closed tube is a convoluted metal tube.
 5. The liquid receptacle of claim 4 wherein ends of the closed tube are secured to the sealing cover.
 6. The liquid receptacle of claim 3 wherein the insert is a coiled tube.
 7. The liquid receptacle of claim 1 wherein the vessel has an insulated outer shell defining an interstitial chamber.
 8. The liquid receptacle of claim 7 wherein a second phase change material is placed into the interstitial chamber of the insulated outer shell.
 9. A liquid receptacle comprising: a vessel for containing a liquid, said vessel having an open upper end and closed lower end and a wall connecting said upper end and said lower end; a sealing cover adapted to engage the open upper end of the vessel and prevent loss of liquid; and an insert adapted to be placed within said vessel, said insert being in contact with the liquid and containing a phase change material which regeneratively absorbs thermal energy from the liquid and then releases the thermal energy to the liquid to maintain the temperature of the liquid within a desired temperature range.
 10. The liquid receptacle of claim 9 wherein the insert is secured to the sealing cover.
 11. The liquid receptacle of claim 10 wherein the insert is a closed tube.
 12. The liquid receptacle of claim 11 wherein the closed tube is a convoluted metal tube.
 13. The liquid receptacle of claim 12 wherein ends of the closed tube are secured to the sealing cover.
 14. The liquid receptacle of claim 9 wherein the insert is a coiled tube.
 15. The liquid receptacle of claim 9 wherein the vessel has an insulated outer shell defining an interstitial chamber.
 16. The liquid receptacle of claim 15 wherein a second phase change material is placed into the interstitial chamber of the insulated outer shell.
 17. A method of regeneratively absorbing thermal energy from a liquid and then releasing the thermal energy to the liquid to maintain temperatures of the liquid within a desired temperature range, said method comprising: dispensing a liquid into a vessel; and sealing the vessel with a cover, said cover including a hollow insert containing a phase change material, with said insert being placed in fluid contact with the liquid when the vessel is sealed with the cover.
 18. The method of claim 17 further comprising thermally pre-treating the insert and phase change material prior to sealing the vessel with the cover.
 19. The method of claim 18 wherein the liquid is a hot liquid and the phase change material contained within the insert is heated prior to sealing the vessel with the cover.
 20. The method of claim 19 further comprising thermally pre-treating the vessel prior to said dispensing the liquid into the vessel. 